1. Field of the Invention
The present invention relates to a method for determining the difference between a sub-Q code and a header of a CD-ROM.
The instant application is based on Korean Patent Application No. 96-15979, which is incorporated herein by reference for all purposes.
2. Description of the Related Art
FIG. 1 shows the structure of a frame of a general CD-ROM. As shown in FIG. 1, the frame of the general CD-ROM includes, sequentially, a synchronizing signal area 101 for containing a synchronizing signal which signals the beginning of the frame, a sub-Q code area 102 for containing a sub-Q code which signals the standard position information of a frame, a header area 103 for recording position information of the respective frames, a user data area 104, and a parity area 105 for containing a parity signal used to confirm whether the user data has been correctly reproduced.
FIG. 2 is a flow diagram for describing the manufacturing process of the general CD-ROM. As shown in FIG. 2, the manufacturing process of the general CD-ROM includes step 201 for controlling the user data so as to fit into the file system structure of the CD-ROM, step 202 for performing an entire control according to the Yellow book, step 203 for performing additional control according to the Red book, and step 204 for forming a master stamper. Here, the Yellow book and the Red book, respectively represent the standard CD-ROM and the CD-DA (compact disk-digital audio) specifications. The Red book is applied since the specification of the sub-Q code is set forth therein. The Yellow and Red books are incorporated by reference herein for all purposes. Therefore, the user data 104 and parity 105, the header 103, and the sub-Q code 102 of FIG. 1 are respectively controlled in steps 201, 202, and 203. Meanwhile, the CD-ROM can be mass-produced by the master stamper formed in step 204, in which the recording structure of the master stamper is the very reverse of that of the corresponding CD-ROM.
As described above regarding FIGS. 1 and 2, the sub-Q code and header information are recorded in the respective frames of the general CD-ROM. Accordingly, most CD-ROM drives search for the specified sub-Q code area to then search for a predetermined frame during a reproducing process, and then search for a specific frame by reading the subsequent header. Here, the sub-Q code and header act as a lapse from the end of the TOC (table of contents) of the CD-ROM to the position of interest on the CD-ROM. Therefore, the larger the difference between the sub-Q and header, that is, the larger the difference between the standard position information and the recording position information of a frame, the longer the access time becomes. Nevertheless, a method for determining the difference between the sub-Q code and the header has not been developed. In particular, in the process of manufacturing a CD-ROM it is very important to determine the difference between the sub-Q code and header with respect to the formed master stamper. The Yellow book standardizes this difference to be within 1 second.